National Science Foundation

About: National Science Foundation is a government organization based out in Alexandria, Virginia, United States. It is known for research contribution in the topics: Galaxy & Population. The organization has 4729 authors who have published 6040 publications receiving 298150 citations. The organization is also known as: NSF & N.S.F..

Observation of Quantum Periodicity in the Transition Temperature of a Superconducting Cylinder

Abstract: Deaver and Fairbank1 and Doll and Nabauer2 have shown experimentally that the flax which is trapped in a superconducting cylinder is an integral multiple of the unit hc/2e. It has been pointed out3’4 that this result follows because the free energy of the superconducting state is periodic in this unit of the flux if the electrons are paired in the manner described by the Bardeen-Cooper-Schrieffer (BCS) theory.5 The free energy of the normal state, on the other hand, is virtually independent of the flux. Consequently, the transition temperature T c , which is the temperature at which the free energy of the normal and superconducting states are equal, must also be a periodic function of the enclosed flux Φ. The magnitude of the change in T c was calculated for a thin cylindrical sample using the BCS model in which the possible pairing of particles with net momentum was included.

A weak Galerkin mixed finite element method for second order elliptic problems

Abstract: . A new weak Galerkin (WG) method is introduced and analyzed for the second order elliptic equation formulated as a system of two first order linear equations. This method, called WG-MFEM, is designed by using discontinuous piecewise polynomials on finite element partitions with arbitrary shape of polygons/polyhedra. The WG-MFEM is capable of providing very accurate numerical approximations for both the primary and flux variables. Allowing the use of discontinuous approximating functions on arbitrary shape of polygons/polyhedra makes the method highly flexible in practical computation. Optimal order error estimates in both discrete H and L norms are established for the corresponding weak Galerkin mixed finite element solutions.

Hyperactivity and Conduct Problems as Risk Factors for Adolescent Development

Abstract: Objective To clarify the developmental risk associated with hyperactive behavior, especially the relationship between hyperactive and conduct problems, in a longitudinal epidemiological design Method A follow-up study of children who were identified, by parent and teacher ratings in a large community survey of 6- and 7-year-olds, as showing pervasive hyperactivity or conduct problems or the comorbid mixture of both problems or neither problem They were later investigated, at the age of 16 to 18 years, with detailed interview techniques as well as parental and self-report ratings and cognitive tests Results Hyperactivity was a risk factor for later development, even allowing for the coexistence of conduct problems Its sequelae included a high likelihood of psychiatric diagnosis, persisting hyperactivity, violence and other antisocial behaviors, and social and peer problems Conclusions The results suggested a developmental pathway through which hyperactivity raised the likelihood of impaired social adjustment, including the development of psychiatric disorders, independently of the existence of conduct problems